A towed agricultural implement is typically connected to a tractor drawbar by a clevis and tongue connection. The clevis provides upper and lower clevis members each defining a draw pin hole, and the tongue defines a draw pin hole and is inserted between the clevis members to align the draw pin holes such that a draw pin can be inserted through them and thereby connect the clevis and tongue.
The clevis may be mounted to the tractor drawbar and the tongue provided by the implement hitch, or vice versa. Essentially the tractor drawbar and the implement hitch are both “tongues”, and the clevis is provided by mounting a hammer strap to the tractor drawbar or to the implement hitch. A hammer strap is simply a steel riser that bolts to the tongue adjacent to the draw pin hole opposite the free end of the tongue and extends away from the tongue and then toward the free end of the tongue and over the draw pin hole in the tongue, creating a recess between the tongue and the hammer strap. The draw pin hole in the hammer strap is aligned with the draw pin hole in the tongue.
The tractor drawbar supports the weight of the front end of the implement being towed, which can be considerable. Thus the tongue of the implement hitch must be connected to the drawbar so that the implement tongue rests on the drawbar. Thus where the hammer strap is mounted to the tractor drawbar, the hammer strap is fastened to the drawbar forward of the draw pin hole in the drawbar, and then extends upward from the drawbar and then rearward over the draw pin hole in the drawbar such that the recess is above the drawbar. The implement hitch rests on the drawbar with the hammer strap above it, and the draw pin is inserted down through the aligned draw pin holes in the hammer strap, implement hitch, and drawbar.
Where the hammer strap is mounted to the implement hitch, the hammer strap is fastened to the hitch rearward of the draw pin hole in the hitch tongue, and then extends downward from the hitch tongue and then forward under the draw pin hole in the hitch tongue. Again the implement hitch tongue rests on the drawbar with the hammer strap below the drawbar, and the draw pin is inserted down through the aligned draw pin holes in the implement hitch, drawbar, and hammer strap.
Pintle hook hitches are also known where a vertically oriented hook is mounted to the towing vehicle, typically a truck. The hook is like a drawbar with a drawpin extending vertical upward. The hitch tongue of the towed vehicle has a ring on the forward end that is dropped down on the hook which extends up through the drawpin hole, and a retainer is connected to the top of the hook to keep the tongue in place. A hitch tongue with a drawpin hole therein can form the ring which drops over the hook, and be supported on the hook the same as on a drawbar.
It is common for implements and other vehicles such as wagons, trailers, and the like to be towed by a variety of different vehicles with different hitches. For example anhydrous ammonia, a very widely used liquid fertilizer product, is transported from a storage site to a farm location in a pressurized tank trailer pulled by a truck at highway speeds. Once at the farm, the truck is disconnected and the trailer is perhaps connected to a farm tractor for towing to a field location and then eventually is connected to the rear end of an applicator implement, such as an air seeder.
Often the delivery truck will have one type of hitch, such as a pintle hook, the tractor another, such as a drawbar with a hammer strap, while the air seeder will have a single tongue drawbar extending rearward. Further with respect to the example of anhydrous trailers, a dealer will typically deliver anhydrous ammonium to a large number of different farmers, each of whom will have a variety of towing vehicle with a variety of hitch mechanisms. Drawpin sizes may vary as well, and it is generally desirable to have the draw pin holes the same size so that a corresponding size of drawpin can be inserted to connect the clevis and tongue with minimal movement at the connection.
Hitch arrangements for road travel also must comply with road safety regulations, especially when transporting hazardous materials such as anhydrous ammonium.
Providing a hitch apparatus that complies with safety regulations and yet is adaptable to a variety of different vehicles is problematic.